<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<style>
    * {
        margin: 0 auto;

    }

    ul {
        margin: 100px;
    }

    ul li {
        width: 120px;
        height: 35px;
        list-style: none;
        perspective: 500px;
    }

    .box {
        position: relative;
        width: 100%;
        height: 100%;
        transform-style: preserve-3d;
        transition: all .4s;

    }
    .box:hover {
        transform: rotateX(90deg);
    }

    .fl,
    .black {
        position: absolute;
        left: 0;
        top: 0;
        width: 100%;
        height: 100%;
        
    }


    .fl {
        background-color: pink;
        z-index: 1;
        transform: translateZ(17.5px);
    }

    .black {
        background-color: purple;
        transform: translateY(17.5px) rotateX(-90deg) ;
    }
</style>

<body>
    <div>
        <ul>
            <li>
                <div class="box">
                   
                    <div class="black">
                        我在这里等你
                    </div>
                    <div class="fl">
                        黑马程序员
                    </div>
                </div>

            </li>
        </ul>
    </div>
</body>

</html>